Estimation of Nitrogen Supply for Summer Maize Production through a Long-Term Field Trial in China

• Main Authors: Shaohui Huang, Wenfang Yang, Wencheng Ding, Liangliang Jia, Lingling Jiang, Yingxia Liu, Xinpeng Xu, Yunma Yang, Ping He, Junfang Yang
• Format: Article
• Language: English
• Published: MDPI AG 2021-07-01
• Series: Agronomy
• Subjects: total nitrogen supply; relative yield; nitrogen use efficiency; summer maize
• Online Access: https://www.mdpi.com/2073-4395/11/7/1358

Supplying adequate nitrogen (N) to meet crop demand is critical for enhancing agricultural sustainability. Not only fertilizer N, but also N from other available sources should be considered in N supply capacity. We conducted a 10-year farming experiment using a split-plot design with two different main fertilizer management approaches and three N application strategies as add-on sub-treatments. Based on the experiment, we estimated the total N supply (TN_supply) for the summer maize cropping system, through considering environmental, soil, crop residue, and fertilizer N sources. An appropriate TN_supply was established by correlating TN_supply with the relative yield (RY), N input and output, and N use efficiency (NUE). The results revealed a wide variation in TN_supply (from 88 to 755 kg ha⁻¹). The RY, N input, and N output fitted well to TN_supply using linear-plateau, linear, and linear-plateau models, respectively. The lower limits of TN_supply for achieving the maximum RY and N output were 361 and 358 kg ha⁻¹, respectively. The relationship between N input and N output was described as linear-plateau. We determined the slope of the linear curve (55.4%) as the lower limit of NUE, beyond which the upper limit of TN_supply was determined to be less than 497 kg ha⁻¹. Thus, appropriate TN_supply values ranged from 325 to 497 kg ha⁻¹ for summer maize production, which could ensure enough N supply for higher yields and avoid excessive N input for higher NUE and lower environmental N loss. Our findings highlight that TN_supply can be an alternative indicator for evaluating N management.